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1980 U1300L
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Discussion Starter #1
Anybody using this size XL? Pros and cons if you have an opinion.
It looks like they are about 43.5 inches, any issues? Thanks for the input.
 

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BenzWorld UNIMOG statesman
Unimog 404.1 Diesel (sold :( )1995 LMTV 1078
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5,857 Posts
Anybody using this size XL? Pros and cons if you have an opinion.
It looks like they are about 43.5 inches, any issues? Thanks for the input.
Not to be a PITA... well.... Ok.... never mind.. I'll be a PITA :p

SEARCH!!!

There is actually a thread.. might even still be on the front page that is on the very same topic.

Just checked.... yep... its still on the front page:rolleyes:

There is plethora of threads here that are a full discussion or side discussion about using XL's. Granted..... it is hard to search by XL too few letters for a typical search engine. An advanced google search targeting this website along with a few other common key words one would see in a thread about tires should bring them up for ya though

Other key words...
Tires
Michelin
1300
1300L
XML's
 

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U1550L/37 Doka, U1700L/38, Merc 1017A
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1,563 Posts
Anybody using this size XL? Pros and cons if you have an opinion.
It looks like they are about 43.5 inches, any issues? Thanks for the input.
i dont think the 11.00x20 can fit correctly on the standard 11x20 mog rims. this tire size requires rims with the VV design or what ever it is called. (higher bead height) and i think it is also ment to go on 7 inch wide rims. they fit deuce wheels perfectly.


coachgeo, for what its worth, i dont recall anyone ever mentioning the 11.00x20 tire size.
 

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1980 U1300L
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34 Posts
Discussion Starter #4
Thanks for the reply. I did the search, but did not find the size in the XL's, but you answered my question, thank you.
 

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U500 with Unicat camper
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798 Posts
FWIW, the 11.00R20 XL has a footprint of 91 sq in; 365/80R20 XZL (same diameter) is ~120 sq in.
The 11.00 is supposed to go on a 7.5 or 8" wide rim.

Charlie
 

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Non MB 1975 Volvo C304, 1958 Kramer U540, 1959 unimog Westfalia 411
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1,381 Posts
Charlie how do you get the area of the footprint for various tires? What I am getting at is with that info I could figure the psi footprint for example a 425/70/20 and a 6500 lb rig. With the collective wisdom here I won't feel lazy for not trying to figure it out. I can crack equations but slow at setting them up. Take the area, square it and divide by the weight?? And the I suppose air pressure will affect the area value. This is simple once I know the procedure for determining the area. I've almost answered my ?
 

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U1550L/37 Doka, U1700L/38, Merc 1017A
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1,563 Posts
Charlie how do you get the area of the footprint for various tires? What I am getting at is with that info I could figure the psi footprint for example a 425/70/20 and a 6500 lb rig. With the collective wisdom here I won't feel lazy for not trying to figure it out. I can crack equations but slow at setting them up. Take the area, square it and divide by the weight?? And the I suppose air pressure will affect the area value. This is simple once I know the procedure for determining the area. I've almost answered my ?
its acutally much more simple. pick two different tires. anything you want. at the same pressure and the same load, the foot prints are equal areas.
 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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its acutally much more simple. pick two different tires. anything you want. at the same pressure and the same load, the foot prints are equal areas.
?????????????????????
 

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Non MB 1975 Volvo C304, 1958 Kramer U540, 1959 unimog Westfalia 411
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Well it's the simple things like interpretation that has me lost,elaborate maybe. Thats like who's on first???I don't get it! Thanks for input and hope I am not derailing orig. subject


Sent from my Autoguide iPhone app
 

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Non MB 1975 Volvo C304, 1958 Kramer U540, 1959 unimog Westfalia 411
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There are two different tires and one has the footprint of average shoe I'll guess and the other likea snowshoe for powder.
 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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Damn storks! I kept a vigil eye and shot down every one that came within 100yds. But they got crafty and flanked me!!
 

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2015 Rubicon Unlimited (Let the shame be upon me!)
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To fill in what Charlie is talking about, an of import to all of us: How to calculate the contact area

Care of Boeing, some folks who care about tires

http://www.boeing.com/commercial/airports/faqs/calctirecontactarea.pdf

Calculating Tire Contact Area
The tire contact area for any aircraft tire is calculated by dividing the single wheel load
by the tire inflation pressure. If the load is expressed in pounds, and the tire pressure in
pounds per square inch, then the area is in inches squared. The same thing works with
kilograms and kg/cm2 - the result will then be in square centimeters.
The shape of the footprint area is usually understood to be a 1.6 ellipse (as referenced
in the US Corps of Engineer's S-77-1 Report), wherein the major axis is 1.6 times the
minor axis. The calculation to solve for the minor axis is .894 times the square root of
the contact area. Note that the major axis runs parallel to the normal direction of motion
of the aircraft, and the minor axis is perpendicular to the major axis.

Example: 777-300 Main Gear Tire Contact Area
For this case, use the maximum taxi weight of 662,000 lbs configuration of the
777-300 as shown in Figure 7.2 “Landing Gear Footprint - 777-200/300” and
Figure 7.3 “Maximum Pavement Loads - 777-200/300.” Figure 7.2 provides the
main gear tire pressure of 215 PSI. Figure 7.3 shows the V(mg) per strut /
maximum load at the static aft center of gravity for this airplane configuration of
313,900 pounds. Given that the 777-300 has six wheels per main gear as shown
in Figure 7.2, to calculate the contact area first determine the load per tire
(313,900 / 6 = 52,317) then to calculate the contact area, divide the load per tire
by the PSI (52,317 / 215 = 243.3 in2 contact area).
The footprint area is a 1.6 ellipse determined as follows:
Minor axis is .894 x square root of the contact area (0.894 x sq root of 243.3 =
13.94 inches minor axis)
Major axis is 1.6 x minor axis (1.6 x 13.94 = 22.30 inches major axis)
 

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2015 Rubicon Unlimited (Let the shame be upon me!)
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So lets say we have U1300 loaded to 16,000lb at 30psi and 60psi.

16,000lb / 4 tires = 4,000lb per tire
4,000lb / 30psi = 133.33"^2 contact area
4,000lb / 60psi = 66.6"^2 contact area

minor axis = .894 x sqrt (contact area) = 10.323"/7.295"
major axis = 1.6 x minor axis = 16.516"/11.673"

16.516" x 10.323" @ 30psi
11.673" x 7.295" @ 60psi

That's a pretty dramatic reduction in contact area that oddly enough has nothing to do with the actual size of the tire. Tire size and subsequent load rating should then be the determining factor for how long and how well any given tire performs in this situation. To take a look at it in very basic terms Load = Patch and Patch should be physically limited by tire carcass dimensions; you cannot have contact patch wider than the physical tread width. Which is a long way of saying contact patch determines tire size and not the other way around.
 

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Non MB 1975 Volvo C304, 1958 Kramer U540, 1959 unimog Westfalia 411
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A little rocket science and poof. That's easier than raising a wheel and setting it in a mold.:bowdown: I thought that was a Sandhill crane I was eating.:surrender:
 

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U1550L/37 Doka, U1700L/38, Merc 1017A
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thanks ACAD for explaining this.

but to make it even simpler:

tire pressure X surface contact area = the load

or

the load / tire pressure = surface area

so as long as the load and pressure are constant, the surface contact area of any tire will be the same ofcourse unless if the rim bottoms out.;)
 

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ex-moglet u1700 (ex U1300L)
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Thank goodness for ACAD_Cowboy! :bowdown:

I can understand how for a specific tyre you can generate a psi/load/footprint relationship, but how does that work between tyres of different sidewall stiffnesseseses? (eses)

:confused::surrender:
 
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